Automatic telephone system.



' W.-KAISLING.

AUTOMATIC TELEPHONE SYSTEM.

, APPLICATION HLED MAY16.1910. I 1,158,927, Patented .5 m TU an 3 m m 5 3w. I 1 U Q m fig Z/Z/IinEssEs W. KAISLING.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAYISJQIYO.

1,158,927, Q Patented Nov. 2, 191 5.-

3 $HEET$SHEET 2- H 5* HT Z/Z/nfnassss fmrsniar WELLIEFL KEIEL mrrig W. KAISLING.

AUTOMATIC TELEPHONE SYSTEM.

APPLlCATION FILED MAY 16. 910- Patemed Nov. 2, 1915.

3 SHEETSSHEET 3.

WELLIQFLKEIELE m M h UZ/IrnEsses UNITED sTATEs PATENT OFFICE.

WILLIAM KAISLING, OF CHICAGO, ILLINOIS, ASSIGNOR T KELLOGG SWITCHIBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEI HONE SYSTEM.

To ail whom it may concern:

Be it known that I, W'ILLiAM KAISLING, a citizen of the United States of America, re-

siding in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is as cification.

. he present invention relates to automatic telephone systems and more particularly to that type known as two-wire or metallic line systems in which the selectors and connectors are directively controlled by the subscriber without the use of any ground connections at the subscriberstelephone, the

object .being to provide a system which is both simple and efiicientand positive in its operation. a

In the system of my'application, I use line switches, one individual to each line, the said line switches being very simple in construction, the wipers having a rotary movement and having access to a group of first selector switches. The said line switches are adapted upon the initiation of a call to automatically connect the calling line with the first idle first selector of the group to which I it has access. The selected first selector and then a second selector and connector are operated to extend the line of thecalling subscriber to the line of the called subscriber.

I have shown no mechanical drawing of a selector or connector'switch in this applica-- tion, the system of my application being adapted to preferably operate in connection with a switch such as is shown in my. appli- V cation filed April 27th, 1910, Serial No.

558,000, although it will operate equally well in connection with any switch having wipers adapted to vcooperate with a bank having contacts arranged in groups, having a primary magnet to give the wlpers a primary adjustment to select a group of contacts, a secondary magnet to give the Wipers a sec ondary adjustment to select a contact in the selected group,.and release magnets to control the release of the wipers. I also use a so-called primary'ofi-normal switch associated with each selector and connector and having contacts moved to their alternate p0 sition upon the first primary movement of r the wipers and a so-called secondary ofi-normal switch having contacts moved to their alternate position upon the first secondary Specification of Letters Patent.

Iatented Nov. 2, 1915.

Applicatioufiled May 16, 1910. Serial No. 561,523.

movement of the wipers, the said switches being restored to normal upon the restoration of the wipers from their respective movements. 7

Referring now to the accompanying drawings, Figure 1, which comprises Part 1, Part 2 and Part 3, discloses a. ten thousand line exchange system adapted to be used for interconnecting its substations in conversational circuits. Fig 2 shows diagrammatically the mechanical switch used in connection with the circuit of line switch C. Fig. 3 shows ,the off-normal springv arrangement used in connection with the switch of Fig. 2.

Assumingnow a system of ten-thousand lines, there would be ten-thousand line switches, such as are shown at C, one for each hne in the exchange, and assuming that the selector and connector switches each have one hundred sets of contacts, on a basis of-ten per cent, trunking, there would be one-thousand first selectors D, one-thousand second. selectors E, and one thousand connectors F. The subscribers lines would be divided into groups of one-hundred lines each and there would be ten first selectors D for the use of each 'one hundred lines. Each subscribers line would also. be multipled to the bank contacts 11, ,12 and 13 of the ten connectors'which have! access to the larly, the wipers of one thousand connectors are multiply connected to the corresponding bank contacts of one-hundred second selectors. The apportionment of values just dition of any particular size exchange or to suit any different percentage'of trunking.

Referring now to the system of Fig. 1, at

given may be varied at will to suit the con- A isshown a well known form of subscrib ers telephone consisting of the receiver'l,

transmitter 2, call-bell 3, condenser 4, im-

pedancecoil 5 and the calling device which includes dial 6 and springs 7 and 8, the operation of the said dial being effective in its return when moved ofI normal to open and close the springs 7 and 8, to interrupt the circuit of the line of subscriber A when making a call. Connecting with the exchange are the two limbs 9 and 10 of the line which terminate at the armatures of the cut-offrelay CO, the said relay being included in the line switch 0, the said switch being individual to the line of the subscriber A. The multiple contacts 11, 12 and 13 are the bank contacts or terminals of connectors which have access to the line. of subscriber at A. The line switch C is adapted upon the initiawhich is adapted to advance the wipers 14,-

15 and 16 to connect with a set of contacts 17, 18 and 19.

At Fig. 2 is shown diagrammatically the switch structure of the line switch 0 consisting of the motor magnet M which is adapted to attract its armature and rotate the ratchet 20 by means of the pawl 21, thereby advancing the wiper 14 toengage one of the contacts 17. To release the switch, the wiper '14 is again advanced until it reaches the position shown now occupied by the wiper 14', the wiper 14 then having advanced to the position now occupied by the wiper 14 The of]? normal springs ON shown in Fig. 3 are moved to their alternate p "ion by the advance of the disk 22 in its a step off-normal, the said disk being secured to the shaft 23 of the switch shown in Fig.2, the springs again returning to their normal position when the switch is advanced to release the connection, the spring 24: then resting in the next notch: The motormagnet M which is used' to move the wipers 14, 15 and 16 to select an,idle first selecto-rD is also used to release the switch to restore it to normal; The first selector switch D includes the primary relay PR, the said relay being" controlled by the calling subscriber at A toling the selection of an idle set offlgntacts in the selected row which lead to a' second selector such as is shown at E. Also included in the first selector D are the primary oif-normal springs PON which are moved to their alternate position upon the first primary movement of the wipers 25, 26 and 27, and the secondary off-normal springs SON which are moved to-their alternate position upon the first secondary movement of the wipers 25, 26, and 27. The secondary off-normal springs SON are restored to their normal position upon the return of the wipers 25, 26 and 27 from their secondarymovement when the switch is released andthe primary'off-normal springs PON are IE-r stored to their normal position when the said wipers have been restored from their primary movement. To restore the wipers after they have connected to a set of contacts, the secondary release magnet SBM is operated to restore them from their secondary movement and the primary release magnet PRM is operated to allow the wipers to restore by a spring from their primary movement. The second selector E is operated in substantially the same manner as the first selector D and includes the same operating magnets as those shown in connection with the first selector D,the operating magnets of the second'selector E having the same reference characters with the. exponent thereafter. The connector F includes the same operating magnets as the first and second selectors, but the secondary'travelof its wipers 31, 32, and 33 .is controlled by impulses from the calling subscriber. The connector F is arranged for selective party line signaling using the well known harmonic system. The switch 0 showninconnection with the connector F is operated to select a y certain frequency of alternating current to ring the bell of the called subscriber. The switch 0 includes the contacts 34: which are adapted to be connected with bythe wiper arm '35 which is advanced by the operation of the magnet 36. The pawl 37 is shown no normally out of engagement with the teeth of the ratchet 38. Normally engaging the pawl 37 is the arm 39 which is secured to the secondary shaft of the switch F. Upon the first secondary movement of the wipers 31, 3

32 and 33 of the switch-F the arm 39 moves away from the pawl 37, allowing'it toengage the teeth of the ratchet 38, so that the wiper arm 35 isheld in engagement with the selected contact 34. The called subscriber at B is connected to the line switch C by the line limbs 9' and 10' which terminate at the contacts of the cut-off relay CO'andfalso 7 connected with the multiple bank contacts of the connector switch Fand the other connectors of the group having-access to the line of the subscriber at B. The line switch C is similar to that shown at C but only part oftlie circuit is shown at C. B, B and B are terminals of subsCriberstelephones similar to that-shown at B, it being assumed that the subscriber at B is one of four the line.

0perati0n.-Assuming now that the subscriber at A desires to connect with the subscriber at B Whose number we will assume is 54324, the subscriber at A removes the receiver 1 from its switch hook, closing an initial energizing circuit through the line relay, LR from ground at normal contact 40 of relay CO, line limb 9, through the telephone of the subscriber vat A, line limb 10, normal contact 41, normal contact-42 of the ofi-normal switch ON, the winding of relay LR to battery, energizing said relay, closing the contact 43, the circuit now dividing and gait passing through the winding of relay to battery, energizing the said relay R. A circuit is now traced through the motor magnet M from ground at alternate contact 44 of relay LR, alternate contact of relay R, through the winding of the magnet M to the alternating generator G. The magnet M now attracts its armature to advance the wipers 14, 15 and 16 to engage the first parties on set of contacts 17, 18 and 19. Assuming that these contacts are connected to a busy first selector as shown at D, there will be a direct ground upon the first contact 17 as will be hereinafter described, and the relays Rand LR will remain energized over a circuit traced from ground at the multiple contact '17, wiper 14, alternate contact 46, dividing and passing through the windings of the re lays LR and R to-battery. Upon the first movement of the wipers of the switch C, the

- off-normal springs ON are moved, to their alternate positions and a ground .is placed upon the multiple contacts 11 traced from the alternate contact 47. The contact 42 disconnects the line relay LR from connection with the line of the subscriber atA,

thereby removing the line control of the v said relay which is now dependent upon the ground connection at wiper 14. The motor magnet M now advances wipers 14,15 and 16 to engage theneXt set of contacts 17, 18 and 19, thesebeing the contacts of the first se- 44 of the relay lector D. This selector'being idle, there will be no ground upon its private contact 17 and the line r'elay LR is deenergized opening the circuit for the magnet M at contact 44 and preventing any further advance of the wipers 14, 15 and 16. The relay R which is sluggish holdsits armature '46 attracted, until a new. locking circuit is established from the first selector D, as will be now described. Upon the deenergization of the line relay LR, a circuit is established for the cut-ofi relay CO from round at alternate"contact R, alternate contact 50 of relay B, through the winding of the cut-off *relay CQ to battery, energizing the said cutoff relay and extending the circuit of the line of the calling subscriber I at A to the first selector D; The primary relay PR is now energized over a circuit traced from ground through the.right-hand winding of the said relay PR, conductor L, alternate contact 40ofrelay CO, line of subscriber at A, "contact 41, line If, the left-hand winding of the relay PRto battery, energizing the said relay and closing a circuit from ground through alternate contact 51, the winding of a clockwise direction until five projections on the periphery thereof have passed below the spring 7 but not opening the contact 7,. 8 until its return. The dial is now released and returned to normal, by the spring shown in connection therewith, opening and closing the contact 7, 8, and interrupting the circuit through the primary relay PR five times,

thereby vibrating its armature 51. The relay MRR being slow to release its armature holds the said armature attracted while the said armature 51 of the relay PR is vibrating. Upon the first deenergization of the said relay PR, a circuit is closed from ground at normal contact 51, alternate con-. tact 53 of'relay MRR, line L normalcontact 54 of the secondary oil-normal switch SON, then dividing and passing through the windings of the secondary relay SR and the primary magnet PM to battery, energizing the said relay and magnet. Theprimary magnet PM is operated upon each dc energization of the .primary relay PR which is effective to step the wipers 25, 26 and 27 to a point opposite the fifth row of contacts 28, 29 and 30 which are the bank contacts leading to the second selector E which has access to connector switches of the fourth hundred group of lines in the fifth thousand group of the exchange.

' traced from the ground at normal. contact 51 of the primary relay PR also hold the armature of the secondary relay SR in its attracted position, due to the said secondary relay SR being sluggish in its action.

After the last impulse -has been trans- The impulses just The subscriber at A now operates the dial-6 in mitted from the primary relay PR, the

armature 51 remains in its attracted position and the secondary relay SR now retracts its armature 55 closin a circuit through the private relay PV rom ground at normal contact 56 of relay PRM, normal contact 55,. normalcontact 57 of. the

secondary oif-normal switch, alternate con .tact 58' of the primary off-normal switch which is now closed, through-the winding of the relay PV to battery, energizing the said relay. A circuit is now closed through the secondary magnet-SM from ground at normal contact 59 of relay PRM, alternate contact 60, through the winding of the said secondary magnet SM to the alternating generator. The secondary magnet now receives impulses from the said generator and steps the wipers 25, 26 and 27 to engage the first set of contacts 28, 29 and 30. of the selected row, the said contacts leading to' a second selector similar to that shown at E.

Assuming that the first set of contacts are the contacts of a busy second selector E, there will be a. direct ground upon the contact 28 as will be hereinafter described, and a locking circuit is now established for the private relay P'V,-from ground at multiple bank contact 28, through the wiper 25, normal contact 61 of relay PR-M, alternate contact .62, and through the winding of the said relay PV to battery. The secondary magnet SM now steps the wipers to engage the second set of contacts, which are the contacts of the idle second selector E. There being no ground upon the private contact 28 of the second selector E, the relay PV denrgiZes opening the circuit for the secondary magnet SM at contact 60 and the wipers 25, 26 and 27 remain in engagement with the contacts of the second selector E. While the wipers 26 and 27 are passing over the line contacts 29 and 30, theircircuit is interrupted at contacts 63 and 4 of relay PV so that no interference will be had with any existing connections. On the first secondary movement of the switch D, the secondary off-normal springs SON moved to their alternate position, disconnecting the secondary relay and primary magnet from the line L at the contact 5 1 and also opening the initial energizing circuit of private relay PV at the contact 57.

Upon the denergization of the relay PV, a

ground is placed upon the multiple contacts 28 from normal contact 62 of relay PV, normal contact 61, and Wiper 25, thus making the switch E busy and unselectable by any other switch such as D. This ground connection also serves to energize the relay: 120.0! switch 'E, the circuit being traced through the low resistance winding of the relay 120, the high-resistance winding 121 to battery.

The subscriber, at 'A now operates the dial 6 to open and close the contact 7, 8

four times, thereby transmitting four-im-.--

pulses from ground at normal" contact 51 of the primary relay PR, alternate contact 53 of relay MRR, line L, normal contact" 63, wiper 26, contact 29, line L normal con-.

tact 65 of the secondaryoiT-normal' switch SON, then dividing and passing through the windings of the secondary relay SR and the primary magnet PM to battery,

energizingthe said relay and magnet. The

the primary relay -PR four impulses from four operate the primary magnet P times to step the wipers 66, 67 and 68't0 a point opposite the fourth row of contacts 69, 70 and 71 in the bank, the sai d con-. tacts leading to a connector switch having access to the group or one hundred lines with which the line of the subscriber at B is associated. The secondary relay SR being a sluggish relay, the contact 72 remains open until the last impulse has been transqnitted through the said relay andmagnet and the relay SR is then deenergized, closing a circuit through the private relay .PV from ground at normal contact 72 of relay SR, normal contact 73 of switch SON,

alternate contact 74 of the primary off- .magnet SM is now energizedby an imfrom the said generator and steps the pulse 66, 67 and 68 to engage the first set wipers to contacts 69, 70 and 71 in the selected row,

which we will assume are the contacts of a busy connector switch similar tothat shown at F. The first set of contacts being those of a busy connector F, there will be a direct -ground upon the private contact 69- as will be hereinafter described and a locking cir cuit will be established for the private relay. PV from the said ground at the said multiple contact 69, through wiper 66, normalcontact 77 of relay PRM, alternate contact 78 of relay PV, through the winding of:

the said relay. to battery. The secondary ma net SM is again operated and steps the wipers 66, 67 and 68 to engage thesec- 0nd set of contacts which are the contacts There 69, 70 nd 71' of the idle connector F.

beingno ground upon private contact 69 of 1 v I the idle connector F, the relay PV" isdeenergized, opening the circuit for the'jsecondary magnet SM at contact/76 and the wipers .66, 67 and 68 remain in engagement .with the bank contacts leading'to the con nector F. The secondaryolf-normal switch SON and the primaryoff-normal switch PO'N ar ejmoved to their alternate position "on the first corresponding movementof the switch: On the denergization of the pr1-, v'ate' relay PV, a direct ground is placed upon the 'pri vate contact 69 from ground at normal contact 78 of the relay PV, conf tact 77 of relay PRM to wiper 66, making this, switch F busy. This ground corinec tion also serves to energize the relay 81 of connector F which is of comparatively low resistance, from battery through the high resistance winding 82 and normal contact .83 of relay 38st.

' mal contactf89 of switch SON then dividing and passing through the windings of the primary magnet PM and the secondary relay SR to battery, energizing the said magnet and relay. The three impulses v whichare transmitted from the primary re:

' lay PR operate the primary magnet PM .three times, which is effective to step the wipers 31, 32 and 33 to a point opposite the third row of contacts 90, 91 and 92 of the bank. The relay SR which is sluggish, holds its armature 93 in an attracted position while the impulses were being transmitted through the winding of the said relay and after the last impulse has been sent, the said armature 93 is retracted. A circuit is now closed through the relay 88 from' ground-at normal contact at of relay PRM line 95, normal contact 93 of relay SR normal contact 96 of switch SON alternate zontact 87 of switch PON which is now moved to its alternate position, through the winding of the said relay 88 to battery, en-

. ergizing the said relay 88. Upon the energization of the said relay 88, a circuit is (losed through the test relay TR from ground at alternate contact 97 of the relay v 88, through the upper winding of relay TR, energizing the said test relay TR, and attracting its armatures. The energization of the said relay 88 also closes the alternate contact 87, thereby cutting olf the primary -'magnet PM and secondary relay STR from connection with line L and cutting in the secondary magnet 5M so that the next set of impulses transmitted will be effective to operate the said secondary magnet SM? The subscriber'at A now operates the dial 6 to transmit two impulses from ground at normal contact 51 of the primary relay PR over the before-traced path to alternate con tact 87 of relay 88 at connector F, then through the winding of the secondary magnet SM to battery, energizing the said manet, and stepping the wipers 31, 32 and 33 to engage the first set of contacts 90, 91 and 92 in the selected row. Upon the first secondary movement of the said wipers, the secondary off-normal switch SON is moved to its alternate position, opening the beforetraced energizing circuit for the relay 88 at contact 96 of the said switch SON but the contact 99 of magnet S1 2 is closed holding the relay 88 energized and due to its sluggi'sh action, holds its armatures attracted and retracts its armatures.

while the secondary magnet SM is operating due to the second impulse, to step the wipers 31, 32 and 33 to engage the contacts 90, 91 and 92 of the line of the called subscriber at B. The relay TR has remainedenergized due to relay 88 being energized.

Called Zine z'cZZe.Assuming now that the line of the calledsubscriber B is idle, there will be no ground upon the private bank contacts 90 and therefore no locking circuit will be established for the lower winding of relay TR. After the last energization of the secondary magnet SM the relay 88 deenergizes opening the circuit for the test relay TR at the contact 97 of the said relay 88 and the said test relay TR deenergizes The deenergization of the test relay TB closes a series circuit through the windings of the relay 101 of the connector Fv and the cut-oil relay C0 of the line switch C. This circuit is traced over the following path: From ground through the winding of the said relay 101, normal contact 102 of the relay TR, normal contact 103 of relay PRM wiper 31 and contact 90, normal contact 47 of oif-normal switch ON, through the winding of the cut-off relay CO, energizing the two said relays 101 and CO. The energization of the cut-off relay CO removes the substation-control ofthe line switch C so that should any subscriber on the line rcmo've his telephone from its switch-hook, the line switch C will not be operated. The energization of the relay 101 closes a circuit through the so-called flip-flop relay FF from ground at normal contact 9% of relay PRM normal contact 10st of relay 86, alternate'contact 105 of relay 101, through the winding of the said relay FF and the interrupter I- to battery. The relay FF is now alternately energized and deiinergized but this hasno efl'ectnpon the circuit or connection at this time. The line of the calling subscriber at A has now been extended from the heavily marked conductors to the line of the called subscriber at B, being open only at the contacts 85 and 100 of relay 80 of the-connector F and connected through the condensers 200 and 201. The

neXt'step is to pick out the proper frequency of'ringing current to operate the bell of the called subscriber at B. The calling subscriber at A now operates the dial 6 to transmit four impulses from the ground at normal contact 51 of the primary relay PR over the before-traced path along the above heavily marked conductor to normal contact 85 of relay 86 at connector F, normal contact 87 of relay 88, alternate contact 89 of the switch SON, and then through the windings of the magnet 36 andrelay 106 of the switch 0, energizing the said magnet and said relay.- 1 Four impulses are transmitted over the G thence over contact 3 1, wiper 35, alternate contact 110 of relay FF, assuming the relayFF is energized at this time, normal contact 107 of relay 106, alternate contact 111 of relay 101, line L wiper33, contact -92, line limb 10, through the condenser,

switch-hook and bell of the called subscriber at B, returning over line limb 9, bank contact 91, wiper 32, line L to ground at alternate contact 112 of the relay FF, ringing,

the bell of the subscriber at B. The circuit of the relay FF is opened at the interrupter I retracting its armatures and placing the windings of the relay 8% in bridge of the line of the called subscriber, over the following traced path: from ground through the lower winding of the said relay 84:, alternate contact 113 of relay101, normal contact 112 of relay FF, line L contact 91, line limb 9 to the telephone of the called subscriber at B, the said circuit being interrupted at the condenser l, then continuing over line limb 10, contact'92, wiper 33, lineLf, alternate contact 111 of relay 101, normal contact 107,

' normal contact 110 of relay FF, through the upper winding of the relay 84 to battery.

Thus, it will be seen that the relay FF- alternately connects the ringing generator G and the relay 84 in bridge of the line of the called subscriber B, but the path for the direct current through the relay 8+1 is interrupted at the condenser at until the receiver 1 is removed from the switch-hook. The subscriber at B now responds to the call by removing the telephone 1' from the switchhook and assuming at that time the relay FF is deenergized, the before-traced circuit through the windings of the relay 81 which was interrupted at the condenser. it is now closed through the transmitter 2, the upper contact, switch-hook and the winding of impedance coil 5, energizing the said relay 8 1 and moving its contacts to their alternate position. Upon the attraction of the armature 83 of relay 84, battery is disconnected from the relayv 81, deenergizing the said relay 81 and also upon the energization of the relay 84, alternate contact 114 is closed and an energizing circuit is established through the relay 86, from battery at the said alternate contact 114C, normal contact 115 of relay 81, through the winding of the said nector F, the conversational circuit connect ing the two subscribers being traced ovgi' the heavily marked conductors. When thef'relay FF is operating to intermittently ringvthe bell of the called subscriber, upon the retrac tion of its armatures 110 and 112, the discharge of condensers at the four subscribers stations on the line is apt to cause a mo mentary attraction of the armatures of relay 84, opening the circuit'for relay 81 at contact 82 and the said relay 81 would deenergize' and close the release circuit for connector switch F, but the said relay 81 being slow to release its armature, the armatures of relay 84 would retract and again close the circuit through the relay 81 at contact 82, preventing the release of the conne'ctorF.

ReZease.The method otreleasing the switches used in establishing the connection is as follows: The subscribers having finishedtheir conversation, the subscriber at A now replaces his receiver upon its switchhook, releasing the line switch C, first selector and second selector E. Upon the restoration of the receiver upon its switchhoolr, the energizing circuit for the primary relay PR of the first selector D is broken by the opening of the upper contacts of the switch-hook and the relay PR- is now deenergized and its armatures detracted. The

tures for the first time since its initial energization when the first selector 1) was first connected with the line of the subscriber at A. Upon the release of the relay MRR, the primary release magnet PRM is energized over a path traced from ground 4 through the winding of the said magnet PRM, normal contact 117 of relay-MRR, alternate contact 58 of switch PON, through the winding of the relay P V to battery, energizing the said magnet PRM and the re lay PV: The closing of the alternatevcontact 56 ofthe magnet PRM retains'the relay R of the switch C in its energized condition, the said relay R being sluggish and retaining its armatures during the interval of the opening of contact 52 of relay MR-R- and the closing of alternate contact of magnet PRH thus preventing the release of the line'switch C until the first selector D has been restored. The closing of the alternate contact 61 of the magnet PRM establishes a locking circuit for the said magnet through the said contact 61, and the alternate contact 118 of switch PON through the altering circuit for the primary release relay PRM will not be broken, although the initial energizing circuit will be opened at contact 117 of relay MRR. Upon the energization of the primary release magnet PRM a circuit is also closed through the secondary release magnet SRM from ground at alternate contact 59 of relay lRM, through the winding of the secondary release magnet SRM to the alternating generator. Impulses of current are now transmitted from the said generator through the winding of the said magnet SIZM which now restores the wipers 25, 2(3 and 27 by a step-by-step movement until they have been returned from their secondary movement. The primary release magnet PRM having upon its energization withdrawn a retaining pawl which held the wipers in their primary position, the said wipers are restored from their primary.movement to normal by a spring.

Upon the restoration of the said wipers to normal, the primary oft-normal switch lON is moved to its normal position, opening the locking circuit for the primary release magnet PRM and the relay PV at the contact 118, thus deiinergizing the said magnet and relay, the said magnet PRM opening the energizing circuit for the magnet SRM at contact 59. The switch D and all its associated mechanism is now at normal. Upon the deenergization of the magnet PRM, the locking circuit for the release relay R of the line switch C is opened at alternate contact 56 of the said magnet PRM. The release relay R now deenergizes and closes a circuit for the motor magnet M from ground at alternate contact 49 of off-normal switch UK through normal contact 45 of relay R and the winding of magnet M, to the alternating generator. Impulses are now transmitted through the'winding of the said magnet M tronrthe said generator and the said magnet M is now operated to advance the wipers 14, 15 and 16 until they have passed beyond the last contact in the bank,

when the. next notch in the disk of Fig. 3 allows the contacts 01 the cit-normal switch ON to move to their normal position,thereby opening the circuit through the motor magnet M- at alternate contact 49. The cutof? relay CO deenergized upon the opening of contact 50 of relay R, and the line switch C and its associated mechanism is now at normal.

The release of the second selector E is accomplished as follows: At the time the primary release magnet PRM of the first selector D was energized to release the switch D, the circuit through the magnet 120 of the second selector E was opened at normal contact 61 of the said magnet PRM, deen ergizing the said relay 120. An energizing circuit for the primary release magnet PRM of the second selector E is now established from battery through the high resistance winding 121, normal contact 122, alternate contact 123 of switch PON through the winding of the said magnet PRM to ground, energizing the said magnet. A circuit is now established through the secondary release magnet SRM' from ground at alternate contact 7 5 of magnet PRH' through thewinding of the said magnet SRM to the alternating .generator. Upon the energization of the primary release magnet PRM a circuit is established through the private relay PV' from ground at alternate contact 124 of magnet PRM', through the winding of the said relay PV' to battery, energizing the said relay and opening the circuit for the wipers 67 and (58 at the contacts 7 9 and 80, so that in the return of the said wipers they will not interfere with any existing connections in passing over the bank contacts. Impulses are now transmitted over the beforetraced path from generator through the secondary release magnet SR'M, the said magnet operating ,to restore the wipers 66, 67 and 68 from their secondary adjustment by a step-bystep movement. The primary release mag net PRM' having withdrawn the retaining pawl which held the wipers 6G, 67 and 68 in their primary adjustment, the said wipers upon their return. from the secondary adjustment are restored from their primary adjustment to normal. The contact 123 of the switch PON' now being open, the magnet PRM is deenergized opening the looking circuit for the relay PV at contact 124, and the said relay PV' is deenergized. The secondary selector E with all of its associated mechanism has now been restored.

To prevent the. second selector E being selected while it is restoring to normal. it is necessary to maintain the bank contact 28 in a busy condition. this being accomplished as follows: hen the relay 120 of switch E is deenergized closing a circuit through the magnet PRM'. the ground at the winding of the magnet PRM is connected to the bank contact through the low resistance winding oi relay 12D. and the winding 121 being of comparatively high resistance, the

private relay PV of any first selector I) seeking connection with-a second selector E will be maintained energized, but suflicient current will not flow through the winding 121 to energize the relay 120.

The release of the connector E which is controlled by the called subscriber at B is accomplished in the following manner: The

subscriber at B having finished his conversation, restores the receiver 1 on its switch .hook, opening the before-traced circuit through the relay 84 at the upper contacts of the said switch-hook and the said relay 84: is now deenergizmi. Contact 114: is now restored to its normal position opening the before-traced circuit through the relay 86 which is now deenergized, restoring its contacts to their normal condition. A circuit through the primary release magnet PRM is now established from battery through the resistance 82, normal contact 83 of relay 84, normal contact 124 of relay 81, alternate contact 125 of switch PONZ normal contact 126 of relay 86 through the winding of the said magnet PRM to ground, energizing the said magnet, moving its contacts to their alternate position and, withdrawing the retaining pawl which held the wipers 3 1, 32-

and 33 in their primary adjustment. A locking circuit for the said magnet PRM is established through contact 127 of the said magnet, alternate contact 128 of switch PON through the protective resistance to battery, this circuit remaining closed and maintaining the magnet PRM energized until the primary off-normal switch PON is restored. The opening of the contact 103 of magnet PRM opens the series circuit through the relay 101 and the cut-01f relay CO allowing the said relays to deenergize and retract their armatures. Upon the ,en-

' ergization of the magnet PRM a circuit is also closed through the secondary release magnet SRM from ground at alternate contact 94, through the winding of the said magnet SRM to the alternating generator.

' 'l Impulses from the said generator are now transmitted through the winding of the said magnet SlEtM operating the said magnet SRM to restore the wipers 31, 32 and stored by spring tension to normal.

- o ens the energizing circuit for the magnet moved its contacts to their normal position upon the restoration of the 'wipersbf the connector. switch F, the locking circuit 3 through the mag-net PRM is opened at contact 128 of the said switch PON denergizing the said magnet PR-M which now RM at contact 94. As previously ole scribed the arm 39 of the switch 0 is secured to the shaft which controls thesecondary movement of the wipers 31, 32 and 33 and when the said shaft is restored, the' arm 39 again engages the pawl-37, moving it out of engagement with the, ratchet 38, and the wiper 35 is restored by the'spring shown in connection-therewith. -The switch F with all its associated mechanism is now restored to normal and the cut-oif relay C0 of the line switch C being restored, the line of the subscriber at B is now in condition for another connection.

Ualled Zine busy-Assuming now that the called subscriber at A has extended his line circuit to the connector and has so far transmitted impulses corresponding to the digits 5, 4, 3 and 2 connecting the wipers 31, 32 and 33 of connector F with the contacts 90, 91 and 92 of the line of the subscriber at B, and assuming that the line of the called subscriber at B is busy, there will be a ground upon the private contact 90, either from the ground at alternate contact 47 of the line switch C if the subscriber at B is making a call, or from the ground through a relay corresponding to the relay 1010f the connectorIF, if the line of the subscriber at B be a called line. This being so, as soon as the secondary magnetSM of the connector F has been operated for the last time and moved the wipers 31, 32 and 33 into engagementwith the contacts 90, 91 and 92 of the line of. the subscriber at B, the armature 99 of the said magnet Sll/P remains in its retracted position and the relay 88 is now deenergized- It will be remembered that the test relay TR was energized through its upper winding from groundthrough alternate contact 97 of relay 88, this circuit being new broken when the relay 88 is deenergized, but a locking circuit is now established through the lower winding of the test relay TR from the ground upon the multiple contacts 90, over wiper 31, normal contact 103 of magnet PRM alternate contact'102 of relay TR, through the lower winding of the said relay TR to battery, thesaid relay remaining energized and holding'its contacts in'their alternate: position. The subscriber at A being unaware atthis time that the line of the subscriber at B is busy, operates the dial 6 to transmit four impulses from the. ground. at'normal contact 51 of relay PR over the before-traced path along the upper heavily marked conductorto normal contact 85 of relay 86, connector F, nor-' mal contact 87 of relay 88, alternate contact.

.89 of switch SON then through the windings of the magnet 36 and relay 106- to battery, these impulses being to select the proper ringing current; '-The said magnet and relay are now operated, the magnet stepping the -wiper 35 around to the fourth contact 3 1v to select the proper frequency to ring the bell of the called subscriber. The test relay TR having remained, energized due' to the connector F connecting with a busy line, the relay 101 is not energized and consequently the flip-flop relay FF also is not energized, so that the selection of the ringing current has no effect upon the line insane? back circuit BB at connector F, over line 129, normal contact 130 of relay 88,- alternate contact 131 of the test relay TR, back j over the upper heavily marked conductor to limb 9, through the receiver 1 of the calling subscriber at A, back over limb 10 over the lower heavily marked conductor and through the left-hand winding of the primary relay PR and the battery to ground. The subscriber at A now replaces his receiver upon its switch-hook, interrupting the circuit through the relay PR- of the first selector D at the contacts of the switch-hook. In this case, the subscriber at A controls the release of all of the switches including the connector F, this release being accomplished in the following manner: Upon the deenergization of the relay PR the main release relay MRR is deenergized releasing the first lay 101 having failed to energize when the connector F connected with the busy line of the subscriber at B, the relay 84 remained disconnected from the line of the said called subscriber at 33, its circuit being interrupted at the contacts 113 and 111 of the relay 101. Therefore, the relay 84 not having energized, the relay 81 remained energized over for the connector F is now established through the primary release magnet PBM over a path traced from battery, through resistance 82 to normal contact 83 of relay 84, normal contact 124 of relay 81, alternate contact 125 of switch PON normal contact 1260i relay '86, through the winding of the said primary release magnet FEM to ground, energizing the said magnet which is now locked up through the alternate.con' tact 127 and alternate contact 128 or switch PON to battery as previously described.

The encrgization of the primary release ma et PREP clpses an energizing circuit through the secon dary release roa-,-;'net SBM and the connector switch F and switch O are restored as previously described.

' Shown in connection with the line switch C is'the busy back circuit BB, the purpose of this being to transmit'a busy signal back to the calling subscriber should all the first selectors D to which the said line switch C has access be busy, this being accomplishedin the following manner: {lpon the initiation of a call by the subscriber at. A, the line switch G automatically operates to con nect the line of the calling subscriber A with an idle first selector D as previously described. Should all of the first selectors D to which the line switch'C has access be busy, the wipers 14-, 15 and 16ers advanced .until they engage an extra-set of contacts 202, 203 and 204 in the bank. There being no ground upon the contact 202, the line relay LR is immediately denergized opening a circuit through the motor-magnet M and closing a circuit through the cut-ofirelay from ground at normal contact 44 of relay LR, alternate contact of relay R which has retained its armatures in an attracted position, through the winding of the said cut-oil relay CO to battery, energizing'the said relay CO. Acircuit is now established from ground at contact 204 over wiper 16, alternate contact 41 of relay CO, line limb 10, through the telephone of the calling subscriber at A, line limb 9, alternate contact 40 of relay CO, wiper 15, contact 203, re-' sistance coil 205, contact 202, wiper 14, alternate contact 46, through the winding of the relay R to battery, retaining the said relay it in its energized conditioni Should the subscriber at Anow'operate the dial (5 to complete connection to a called sub scriber, the last traced circuit would be opened at the contact 7, 8, but the relay B being sluggish would retain its armatures in their attracted position. The subscriber at A would now take up the receiver 1 and receive a characteristic busy signal traced from the busy back circuit BB to contact 203, wiper 15, alternate contact 40, line limb 9, through the receiver of the callingsubscriberat A, line limb 10, alternate contact 41, wiper 16 and contact 204 to ground. The subscriber would now replace tl'i; receiver 1 upon its switch hook opening the circuit forthe relaylit which would deener gize and close a release circuit through the motor magnet M, restoring the switch as previously described.

While 1 have shown a number of batteries, it will lie-understood that they are all one and the same battery, having been shown in this mahner for convenience in making the drawing and describing the operation of the system. The same is also true of the alternating generators used for operating the motor magnets, but 1 preferably employ four separate alternating generators for supplying ringing current as shown in connection with the ringing switchO.

.What I claim as new and desire to secure by Letters Patent is:

1. In an automatic telephone system, the combination of a calling subscribers telephone line with a line switch for said line, a source of current, a plurality of selector switches, a line relayand a release relay for said switch energized by said current upon the initiation of a call from said subscriber, and means for thereafter operating said line switch to select an idle one of said selector switches, substantially as described.

2. In an automatic telephone system, the combination of a calling subscribers tele phone line with a line switch for said line, a plurality of selector switches, a line relay and a release relay for said switch adapted to be energized upon the initiation of a call from said subscriber, means for thereafter operating said line'switch to select an idle one of said selector switches, means for deenergizing said line relay and retaining said release relay energized upon the said selection of an idle'selector, and means under the control of the calling subscribers to thereafter det ne'rgize said release relay, whereby said line switch isrestored, substantially as described.

3. In an automatic telephone system, the

combination with a calling subscribers metallic circuit telephone line, of a selector switch connected to said line, bank contacts for said switch arranged in groups, movable wipers adapted'to coiiperate with said contacts, a primary magnet forsaid switch, a

secondary magnet for said switch, means under the control of the subscriber to operate said primary magnet, whereby said wipers select a group of contacts, means for thereafter operating said secondary magnet whereby said wipers connect with a contact in the selected group, a primary release magnet for controlling the restoration of the wipers from their primary movement, a secondary release magnet for controlling the restoration of the wipers from their secondary movement, and means under the control of the subscriber forinterrupting the metallic circuit of the telephone line for operating said release magnets, whereby said wipers are restored, substantially as de; scribed. i

4. In an automatic telephone system, the combination with a calling subscribers telephone line, of a selector switch connected to said line, bank contacts for saidswitch arranged in' groups, movable wipers adapted to cooperate with said contacts, a pair of release magnets for said switch, a primary relay. in bridge of said telephone line, and energized over said line, a secondary relayn'elatively slow to release its armature, a third relay relatively slow to wipers release its armature,

trolled by said secondary relay operating re? sponsive to cessation of 531d. vibrationsto adjust said wipers to select a contact in the group, and means under the controlof the subscriber to denergize said primary relay,-

whereby said third means operated by said third relay to successively operate said wherebv said wipers are relay is denergized, and

release magnets u restored, substantially as described.

5. In an automatic telephone system, the

the denergization of combination with a calling subscribers telephone line, of a plurality of selector switches, a line switch for saiddiiitzgbank contacts for said switch connected to said selector switches, wipers for said switch adapted to cooperate with said contacts, means operative upo'n'the initiation of a call from said subscriber to move said wipers to test all of said contacts, a release relay for said switch energized while said are testing said contacts, means for including said release relay in circuit of said telephone line, a characteristic signal transmitted to the calling subscriber to notify said subscriber that all of the contacts havebeen tested, and meanscontrolled by the said subscriber to de'nergize said release relay, whereby said wipers are restored.

6. In a telephone system, of acalling'subscribers telephone line with a line switch for said line,'a; plurality of trunk lines leading therefrom, means for operating said switch upon the initiation of a call from said subscriber test said trunk lines to seek connection with an idle one, a release relay for said line switch energized over a local circuit while said switch is testing said trunks, and means for thereafter opening said local circuit and including said relay .in'circuit with said telephone line. 1

7. In a telephone system, the combination of a calling subscribers telephone line with a line switch for said line, a 'plurality of trunk lines leading therefrom, means 'ior the, combination to automatically operating said switch upon the initiation of a call from said subscriber to automatically test all of said'trunk lines, a characteristic signal thereafter transmitted to said subscriber to notify said subscriber that all of said trunk lines are busy, a release relay for said line switch energized overa la -a circuit while said-switch is testing said trunks, and means for thereafter openingsaid local circuit and including said relay in'circuit with said telephone line.

of a calling subscribers telephone line with a 8. In a telephone system, the combination connector switch operated to connect said telephone line to the line of a called subscriber, said called line having a. plurality of su scribe'rs" telephones connected thereto, an auxiliary switch associated with said connector switch, operated to select the proper ringing current to ring the bell of the desired subscriber on the called line, and holding means mechanically connected to a movable element of the connector'switch whereby the restoration of said connector restores said auxiliary switch.

9. In a telephone system, the combination of a calling subscribers telephone line with a connector switch operated to connect said telephone line to the line of a called subscriber, said called line having a plurality of subscribers telephones connected thereto, an auxiliary switch associated with said connector switch, a magnet and a relatively slow relay for said auxiliary switch, means controlled by the calling subscriber to vibrate the armature of thesaidmagnet while the' relay holds its armature attracted, a wiper for said auxiliary switch actuated responsive to saidvibrations to select the proper ringing current to ring the bell of the desired subscriber on the line, the said relay thereafter retracting its armature, whereby said ringing current is applied to said called line.'y 10. A telephone system including a' telephone line extending'from' a substationto a line-switch at the exchange, trunks leading from said switch, means for operating said 7 switch upozi initiation of a call over said line to successively test said trunks, a relay energized upon initiation of the call, means v for maintaining said relay energized by ourticisignal to. the

rent over said line if all of the trunks are busy and release means for said switch con trolled by said relay.

1].. -A telephone system mcluding a tele-' phone line extending from a substation to, a"

line-switch at the exchange, trunksleading from said switch, means for operating said switch upon initiation of a call over said line to successively test said trunks, arelay energized upon initation of the call, tneans for maintaining said relay energized by cur rent over said line if all of the trunks are busy, and means for releasing said switch,

controlled by said relay when thus maintained energized.

12. A telephonesystem including a telephone line extending from a substation to a -line-switch- 'at thejexchange, trunks leading from said switch, means for operating-said switch uponinitiation of a call over said line to. successively test'said trunks, a relay energized uoon initiation of the call, means for maintaining .saidrelay energized by current over said line if all of thetrunks are busy, means for tr ea substation if all of iiiisinitting a characteris all:

said connector switch, operated to select the proper ringingcurrent to ring the bell of the desired subscriber on the called line, and mechanical means linking said connector and said ringing switch whereby the resto ration of said connector restores said ringng switch.

14. An automatic switch including 'suitable talking conductors, a ringing switch,

having a plurality of ringing contacts and an .associated Wiper; a drivingmagnetifor operating said wiperto select one of said contacts, anzimpulse'circuit-for said magnet,- a slowacting relay connected in -multiple, with said magnet and adapted toholdits' armature attracted during .the operation of said magnet, and a connection extending from said wiper through a normally closed contact of said relay to one of the talking conductors of said switch. A 15; A ringing switch comprising a plurality of ringing contacts and a cooperating wiper, a magnet for operating said wiper to select oneof said contacts, a slow-a'cting relay connected in multiple circuit with said magnet, and a. ringing circuit extending from said wiper through a normally closed contact on saidrelay.

16. A telephone system comprising a call ing telephone line, a line switch individual thereto, trunks extending from said line switchfa line relay and a release relay for said switch energized by current from said source upon initiation of a call over said line, an operating magnet for said switch having a circuit including normally open contacts onboth the said relays and effective responsive to said energization thereof, and

means for deenergizing said line relay and placing said release relay under control of the calling substation upon selection of an idle one of said trunks.

17. A line switch for telephone systems comprising contacts and co'iiperating wipers, a line relay, a release relay adapted to be energized responsive to the line relay, a mo.-

t'or magnet for said switch, a circuit for said motor magnet including normally open contacts of saidrelays, and a release circuit 125 normally closed contact of said release relay and an off-normal contact.

for said switch including said magnet, a

18. A telephone svstem comprising a calling substation telephone line haying a line switch connected therewith, a's'ource of ouring substation telephone line having a line switch connected therewith, a plurality of selector switches, a line relay and a release relay for said switch energized upon initial closure of the calling linecircuit at the sub- 15 station thereof, means for thereafter operating saidline switch to select an idleone of said selector switches, means for deenergizing said line relay and maintaining said release relay energized upon said selection of an idle switch, means for deenergizing said release relay; responsive to interruption of the line circuit for restoring said line switch.

, 20. A telephone system comprising a calling substation telephone line having a connector switch operated to connect said lineto a called line,

, sociated with'said called line, an auxiliary 7 switch for said connector operated to select a plurality of substations asthe propercringing current to ring the bell of the desired substation on the called line,

holding means for said auxiliary switch, means whereby said connector switch is re-' stored, and a mechanical link from said holding means to the wiper shaft of said connector whereby the restoration of said connector will bring about the restoration of said auxiliary switch.

21. An individual line switch for telephone systems comprising contacts and co.-

operating wipers, a line relay, a release re- 40 lay adapted to be energized responsive to energization of the line relay, a motor magnet for. saidswitch, an o erating circuit for said motor magnet inclu ing normally open contacts of said relays, and a release circuit forsaid switch; including said magnet, a

'normally closed contact of said release relay and a normally open off-normal contact.

Signed by me at Chicago, county of Cook,

and State of Illinois, in the presence of two witnesses. y

' WILLIAM KAISLING. Witnesses:

GEORGE E. MUELLER, anaonrn E. GRmR; 

